紫草素通过PI3K/Akt通路抑制氧糖剥夺诱导的大鼠原代皮层神经元凋亡

目的:探讨紫草素对氧糖剥夺(OGD)损伤模型中大鼠原代皮层神经元的作用及机制。方法:用不同浓度(0. 02、0. 2、2和20μmol/L)紫草素对大鼠原代皮层神经元经进行预处理,再经OGD损伤处理,用乳酸脱氢酶(LDH)释放法和荧光素二乙酸酯/碘化丙啶(FDA/PI)双染法分别检测神经元活性和凋亡情况,选择最适紫草素浓度。然后,在加入紫草素之前提前加入LY294002(PI3K/Akt信号通路抑制剂,1μmol/L),用Wesern blot法检测神经元p-Akt(Ser473)水平变化,用LDH法和FDA/PI双染法检测神经元活性和凋亡率变化。结果:0. 2、2及20μmol/L的紫草素可显著提高神经元存活率(P 0. 05),同时还可使神经元内p-Akt(Ser473)水平显著升高(P 0. 05); LY294002可显著阻断紫草素对神经元p-Akt(Ser473)水平和凋亡率的影响(P 0. 05)。结论:紫草素可通过激活PI3K/Akt通路来减少OGD诱导的大鼠原代皮层神经元凋亡。     

氧葡萄糖剥夺-再恢复后抑制小胶质细胞TLR9激活对神经元的保护作用

目的:观察氧葡萄糖剥夺-再恢复(OGDR)后小胶质细胞BV-2 Toll样受体9(TLR9)激活对神经元凋亡的影响。方法:对BV-2细胞或TLR9-siRNA转染的BV-2细胞进行OGDR处理4 h后,将细胞上清添加至OGDR处理4 h的小鼠原代皮层神经元中,继续正常培养24 h后,倒置显微镜下观察神经元形态变化,TUNEL染色检测神经元凋亡,Western blotting检测神经元caspase-3蛋白的表达。实验分为正常BV-2组、negative control-siRNA组、TLR9-siRNA组、OGDR组、OGDR+NC-siRNA组、OGDR+TLR9-siRNA组和对照组(神经元OGDR后不添加BV-2细胞上清)。结果:OGDR后神经元胞体肿胀,折光性下降,出现空泡样变,轴突变细、扭曲、断裂。TUNEL染色各组均可见绿染凋亡小体。与对照组比较,其它组的caspase-3蛋白表达升高(P0.05);与正常BV-2组比较,OGDR组和TLR9-siRNA组的caspase-3蛋白表达升高(P0.05);OGDR+TLR9-siRNA转染组与TLR9-siRNA转染组和OGDR组比较,caspase-3蛋白表达下降(P0.05)。结论:OGDR后BV-2细胞TLR9激活致神经元凋亡增多,caspase-3蛋白表达升高;抑制TLR9表达后,神经元损伤减轻。     

Metformin protects PC12 cells against oxygen-glucose deprivation/reperfusion injury

Oxidative stress has a causative role in ischemic reperfusion-induced cell death. Evidence has shown that metformin is capable to reduce ischemic reperfusion injuries. The current study investigated the effect of metformin on ischemia/reperfusion-induced apoptosis in PC12 cells by evaluation of Bcl-2 family proteins expression. Cells were exposed to a time-dependent in vitro oxygen-glucose deprivation/reoxygenation (OGD/R) injury and then treated with metformin. The intracellular reactive oxygen species (ROS) levels were measured. Western blotting was used to examine the expression of anti- and pro-apoptotic proteins. Moreover, the number of apoptotic cell death was evaluated by TUNEL assay. Our results showed that metformin attenuated ROS generation, downregulated pro-apoptotic BAX expression, and upregulated expression of the Bcl-2 protein in the PC12 cells. Moreover, metformin reduced cell death under OGD/R condition which was confirmed by lower apoptotic cell death in the TUNEL assay. These findings suggest that neuroprotective effect of metformin on OGD/R-induced cell death is possibly mediated by inhibition of ROS-induced apoptosis pathway.     

丁苯酞可减轻缺氧缺糖条件下血管内皮细胞的线粒体损伤

 目的:探讨丁苯酞（DL-3-n-butylphthalide, NBP）对缺氧缺糖(oxygen-glucose deprivation, OGD)条件下内皮细胞中线粒体的保护作用及相关机制。方法:对人脐静脉内皮细胞(human umbilical vein endothelial cells, HUVECs)予以OGD损伤,使用 MitoTracker Green对线粒体进行定位并观察线粒体形态的变化。使用MitoSOX Red标记线粒体内的活性氧簇（reactive oxygen species,ROS）,免疫荧光法观察NBP对OGD条件下细胞线粒体内ROS产生的影响。使用SOD活性试剂盒检测NBP对OGD条件下HUVECs内SOD活性的影响。结果:NBP明显减少了OGD诱导后内皮细胞中线粒体的断裂,抑制了线粒体内ROS的生成,提高了OGD诱导后细胞内SOD的活性。结论:NBP可能是通过保护OGD条件下内皮细胞线粒体的功能和增加细胞内ROS清除,减少线粒体内ROS生成,最终减轻了线粒体损伤。     

miRNA-21减轻氧糖剥夺对PC12细胞的损伤

目的:探讨微小RNA(miRNA)-21对低氧缺血损伤PC12细胞的影响。方法:体外培养PC12细胞,建立氧糖剥夺(OGD)损伤模型。细胞随机分为对照组、OGD组、阴性对照序列+OGD组、miRNA-21 inhibitor+OGD组和miRNA-21 mimic+OGD组。通过采用CCK-8、real-time PCR、Western blot等技术探讨miRNA-21对OGD损伤PC12细胞的影响和机制。结果:降低miRNA-21的表达,受OGD损伤的PC12细胞活力明显下降;增加miRNA-21的表达,受OGD损伤的PC12细胞活力明显增加。进一步发现miRNA-21促进OGD损伤PC12细胞的AKT磷酸化。结论:miRNA-21明显增加OGD损伤PC12细胞的活力,其机制可能与激活PI3K/AKT信号通路有关。     

龙胆苦苷对新生大鼠氧糖剥夺再灌注损伤海马神经元Caspase-3、Bax和Bcl-2表达的影响

目的探讨龙胆苦苷(GP)对新生大鼠氧糖剥夺再灌注损伤海马神经元的抗凋亡保护作用及机制。方法采用无糖培养基加缺氧法建立原代新生大鼠海马神经元氧糖剥夺再灌注损伤模型,同时给予不同浓度的龙胆苦苷进行干预。应用Hoechst 33342染色法检测神经细胞的凋亡,并计算凋亡率;化学比色法测定神经细胞乳酸脱氢酶(LDH)漏出率;RT-PCR和Western blotting技术检测凋亡相关因子Caspase-3、Bax和Bcl-2 m RNA和蛋白的表达。结果与正常组比较,模型组Hoechst 33342染色神经元凋亡率明显升高,LDH漏出率增加,Caspase-3、Bax m RNA和蛋白的表达水平上调,Bcl-2 m RNA和蛋白的表达水平下降。与模型组比较,龙胆苦苷(40、20、10mg/L)可显著降低氧糖剥夺再灌注损伤神经元的凋亡率和LDH漏出率;龙胆苦苷(40mg/L)可明显抑制Caspase-3、Bax m RNA和蛋白的表达,升高Bcl-2 m RNA和蛋白的表达。结论龙胆苦苷对新生大鼠海马神经元氧糖剥夺再灌注损伤所诱发的神经细胞凋亡具有保护作用,其机制可能与上调Bcl-2表达,抑制Caspase-3、Bax表达有关。     

Metabotropic glutamate 1 (mGlu1) receptor antagonists enhance GABAergic neurotransmission: a mechanism for the attenuation of post-ischemic injury and epileptiform activity?

Selective antagonists of mGlu1 metabotropic glutamate receptors attenuate neuronal death in models of cerebral ischemia. Because GABAergic mechanisms have recently been proposed to contribute to these neuroprotective effects, we examined the effects of selective mGlu1 antagonists characterized in our laboratory on GABAergic transmission in three different models of neuropathology. In rat organotypic hippocampal slices exposed to oxygen-glucose deprivation, the mGlu1 antagonists AIDA, CBPG and 3-MATIDA reduced CA1 pyramidal cell loss when added to the medium during the insult and the subsequent recovery period. This effect was mimicked by the GABA(A) and GABA(B) agonists muscimol and baclofen and partially prevented by the antagonists bicuculline and CGP 55845. In gerbils subjected to global ischemia, protection of CA1 pyramidal cells by transdialytic perfusion of AIDA and CBPG was associated with a significant increase in the basal and ischemic output of GABA and minor changes in the output of glutamate. In a mouse cortical wedge model, both muscimol and 3-MATIDA reduced the frequency of spontaneous bursts induced by 4-aminopyridine and this reduction was prevented by co-perfusion with bicuculline. Taken together, our results suggest that the release of GABA, and the subsequent activation of GABA receptors, may contribute to the attenuation of post-ischemic neuronal damage and epileptiform activity induced by mGlu1 receptor antagonists.     

Neuroprotective and neurotoxic effects of monoamine oxidase-B inhibitors and derived metabolites under ischemia in PC12 cells.

Selegiline and rasagiline are selective and irreversible monoamine oxidase-B inhibitors that exert neuroprotective effects in various preclinical models. The aim of the present study was to examine the effect of selegiline and its major metabolite, L-methamphetamine in comparison to rasagiline and its major metabolite, 1-R-aminoindan on oxygen-glucose deprivation induced cell death in nerve growth factor (NGF)-differentiated pheochromocytoma (PC12) cells. Our results show that selegiline reduces oxygen-glucose deprivation induced cell death by 30%. When the cultures were treated with rasagiline at similar concentrations, cell death induced by oxygen-glucose deprivation was reduced by 45-55%. L-methamphetamine, a major selegiline metabolite, but not 1-R-aminoindan, the major rasagiline metabolite, enhanced oxygen-glucose deprivation-induced cell death by 70%. Under normoxic conditions, both metabolites lack neurotoxicity. Concomitant exposure of the cultures under oxygen-glucose deprivation, to a combination of either selegiline and L-methamphetamine or rasagiline and 1-R-aminoindan, indicated that L-methamphetamine, but not 1-R-aminoindan, blocked the neuroprotective effect of the parental drug. These results suggest there may be a neuroprotective advantage of rasagiline over selegiline.     

Ischemic insult exacerbates acrolein-induced conduction loss and axonal membrane disruption in guinea pig spinal cord white matter

Cellular destruction following ischemic insult may be due to secondary injury mechanisms, not the oxygen-glucose deprivation itself. We have examined the effect of acrolein, an aldehyde product of lipid peroxidation (LPO) and oxidative stress, on the axons in isolated guinea pig spinal cord white matter following ischemic insult. We have found that acrolein at 50 microM, which is unharmful to spinal cord when applied alone, causes action potential conduction failure and membrane disruption following 1 to 2 h of exposure when applied during the reperfusion period. Ischemic insult also exacerbates the effect of acrolein at 200 microM, which does inflict functional and anatomical damage when applied alone. Unlike metabolic poisoning, acrolein-mediated damage is not a function of axonal size and does not affect the refractoriness in response to dual and multiple stimuli. These results indicate that spinal cord axons, in addition to experiencing elevated free radicals, are more vulnerable to acrolein attack when the level of oxygen and glucose is low. We conclude that free radicals and lipid peroxidation in general, and acrolein in specific, may play a critical role in cellular destruction and functional loss in such injury.     

丹参酚酸通过抑制超氧阴离子生成保护SHSY5Y细胞的研究

目的:观察丹参酚酸对体外缺氧缺糖SHSY5Y细胞的保护作用及超氧阴离子生成对该保护作用的影响。方法:体外培养SHSY5Y神经母细胞瘤株,以缺氧缺糖(OGD)、丹参酚酸(100 mg/L)及三亚乙基四胺(1 mM)处理,以MTT检测SHSY5Y细胞活性,应用calcein-AM、HEt和fluo-3/AM的荧光强度测定OGD后SHSY5Y细胞线粒体通透性转换孔开放、细胞内超氧阴离子和钙离子的浓度。结果:丹参酚酸可以提高OGD后SHSY5Y细胞的活性,降低OGD后calcein-AM、HEt和fluo-3/AM的荧光强度。丹参酚酸的神经保护作用可被三亚乙基四胺阻断。结论:丹参酚酸通过减少SHSY5Y细胞超氧阴离子生成,进而抑制线MPTP开放及细胞内钙超载,从而达到保护SHSY5Y细胞对抗OGD的细胞损害的作用。